GRASS GIS manual: v.db.univar

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NAME

v.db.univar - Calculates univariate statistics on selected table column for a GRASS vector map.

KEYWORDS

vector, statistics

SYNOPSIS

v.db.univar
v.db.univar help
v.db.univar [-e] table=string column=string [database=string] [driver=string] [where=string] [--verbose] [--quiet]

Flags:

-e: Extended statistics (quartiles and 90th percentile)
--verbose: Verbose module output
--quiet: Quiet module output

Parameters:

table=string: Name of data table
column=string: Column on which to calculate statistics (must be numeric)
database=string: Database/directory for table
driver=string: Database driver
where=string: WHERE conditions of SQL statement without 'where' keyword

DESCRIPTION

v.db.univar calculates basic univariate statistics for numeric attributes in a data table. It will calculate minimum, maximum, range, mean, standard deviation, variance, coefficient of variation, quartiles, median, and 90th percentile. It uses db.select to create list values for statistical calculations. NOTES If the database and driver are not specified, the default values set in db.connect will be used.

EXAMPLE

In this example, random points are sampled from the elevation map (North Carolina sample dataset) and univariate statistics performed:

g.region rast=elevation -p
v.random output=samples n=100
v.db.addtable samples column="heights double precision"
v.what.rast samples raster=elevation colum=heights
v.db.select samples

v.db.univar samples colum=heights

AUTHOR

Michael Barton, Arizona State University

and authors of r.univar.sh

Last changed: $Date: 2011-09-04 06:23:30 -0700 (Sun, 04 Sep 2011) $

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